This invention relates to a rotary electrical connector assembly for use primarily but not exclusively in making an electrical connection between a vehicle electrical system and a component carried by and rotatable with the steering shaft of the vehicle.
It is known to utilize a slip ring assembly to make a rotating electrical connection to a component, for example a steering wheel mounted horn switch of a vehicle, but it is found that such electrical connections may not exhibit the necessary reliability for making connection to a safety critical component such as the inflation system of a steering wheel mounted air-bag assembly.
It has previously been proposed to minimise this difficulty by utilizing a high reliability connector such as a so called "clock-spring" or spiral cassette type connector in safety critical applications. This type of connector includes a spirally wound flat strip including at least one conductor, the strip being wound so as to form a coil encircling the axis of rotation of the steering shaft, electrically to interconnect at least one terminal member on a fixed housing part and at least one terminal member on a housing part rotating with the steering shaft. The spiral conductor coil is designed to accommodate the range of rotation of the steering shaft, usually no more than two or three revolutions in either direction from a central position, the coil being wound tighter or unwound dependent upon the direction of rotation. There is of course no sliding electrical connection and the integrity of the electrical connection between the terminals is certain to be maintained through the intended rotational range.
It will be recognised that the connector is designed to be operated such that at the central point in the range of movement of the steering shaft, the coil is at the mid-point of its winding movement. Such an orientation of the "clock-spring" relative to the steering shaft is relatively easy to ensure during original assembly of the vehicle but may be lost during subsequent removal and reassembly of the steering assembly of the vehicle which may become necessary in use. Clearly should a "clock-spring" connector be removed when at a position corresponding to the steering being at one extreme and then reassembled with the steering at its opposite extreme, then there is a serious risk of failure of the connector through over tightening or over-unwinding of the coil in use and it is an object of the present invention to minimise this risk.